[PATCH 5/8] integrity: IMA policy open

Sequentialize access to the policy file - permit multiple attempts to replace default policy with a valid policy Signed-off-by: Mimi Zohar <zohar(a)us.ibm.com&gt; Acked-by: Serge Hallyn <serue(a)us.ibm.com&gt; Signed-off-by: James Morris <jmorris(a)namei.org&gt; --- diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index 95ef1ca..573780c 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -277,16 +277,30 @@ static struct dentry *runtime_measurements_count; static struct dentry *violations; static struct dentry *ima_policy; +static atomic_t policy_opencount = ATOMIC_INIT(1); +/* + * ima_open_policy: sequentialize access to the policy file + */ +int ima_open_policy(struct inode * inode, struct file * filp) +{ + if (atomic_dec_and_test(&policy_opencount)) + return 0; + return -EBUSY; +} + /* * ima_release_policy - start using the new measure policy rules. * * Initially, ima_measure points to the default policy rules, now - * point to the new policy rules, and remove the securityfs policy file. + * point to the new policy rules, and remove the securityfs policy file, + * assuming a valid policy. */ static int ima_release_policy(struct inode *inode, struct file *file) { if (!valid_policy) { ima_delete_rules(); + valid_policy = 1; + atomic_set(&policy_opencount, 1); return 0; } ima_update_policy(); @@ -296,6 +310,7 @@ static int ima_release_policy(struct inode *inode, struct file *file) } static struct file_operations ima_measure_policy_ops = { + .open = ima_open_policy, .write = ima_write_policy, .release = ima_release_policy }; -- 1.5.6.6